in reply to Local for lexicals
Update: Did you ever want to just take back something ignorant? Yeah, all the time. So the original part of my post is left below for posterity to snigger at. And it's probably obvious that you can get your desired effect with a string-eval, with all the safety caveats that that implies. Nevertheless, here it is:
Caution: Contents may have been coded under pressure.
#!perl use strict; use warnings; sub lambda { my $varname = shift; my $fn_body = shift; my $estring= "sub { my \$$varname = shift; $fn_body }"; print "Evaling $estring\n"; eval $estring; } my $x = 3; my $closure = lambda 'x' => q { $x**2 }; for (1..4) { print $closure->($_), "\n"; } print "And my X is $x\n";
--- original below ---How close is this to satisfactory? (Packagery is just in there to test cross-package calling.) It's not actually using lexical x, but I can't see why that's important (though it could conceivably be, if your function were to call other functions).
#!perl use strict; use warnings; sub lambda { my $varname = shift; my $fn = shift; my $pkg = do { no strict 'refs'; * {caller().'::'} }; sub { local ${$pkg}{$varname} = \shift; $fn->() } } package a::b::c; our $x; my $closure = main::lambda 'x' => sub { $x**2 }; for (1..4) { print $closure->($_), "\n"; }
Caution: Contents may have been coded under pressure.
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Re^2: Local for lexicals
by LanX (Saint) on Aug 13, 2009 at 10:52 UTC | |
by Roy Johnson (Monsignor) on Aug 13, 2009 at 14:10 UTC |
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